A transverse leaf spring type suspension including a leaf spring mounted transversely of a car body so as to serve also as a lower arm or upper arm is disclosed, for example, in Japanese Disclosure Gazette No. 1983-501626 (International Publication No. WO 83/01758). The suspension of this type can do away with both the coil spring and the stabilizer.
FIG. 4 of the accompanying drawing schematically shows the leaf spring 1 included in the conventional suspension of this type in which the leaf spring 1 serves also as the lower arm, and the wheels 2. The wheels 2 are operatively associated by the respective knuckles with the opposite ends of the leaf spring 1. This leaf spring 1 has a linear longitudinal axis perpendicular to the central axis 0 of the car body and is supported by the car body at two intermediate support points P.
However, it will be impossible to mount the leaf spring 1 linearly between the right and left wheels 2 when various components such as the engine, the transmission, the differential gear and an axle beam are positioned between these wheels 2.
FIG. 5 illustrates a relationship between the upper arms 3 and the associated wheels 2. To obtain a suspension geometry for high maneuverability and stability, each rocking shaft L of the associated suspension arm, such as the upper arm 3, makes an angle with the central axis 0 of the car body. When the linear leaf spring 1 is employed in such suspension, the axis of the leaf spring 1 will not be perpendicular to the rocking shafts L, causing a torsional moment to be exerted on the leaf spring 1 at its support points as the wheels 2 move vertically. To achieve a lightweight vehicle, the leaf spring 1 may be formed by use of suitable synthetic resin, such as fiberglass reinforced plastic (FRP), but a leaf spring 1 made of such material will not be adequately resistant to the torsional moment and, therefore, the linear leaf spring 1 will be inadequate in this case.